Dome Skylight: Revolve won't move with roof plane

[Anonymous]

I am fixing some families in the corporate revit library, and we have a circular skylight with domed glazing that is free standing.  I am making a roof based version so that it is hosted on the roof and will cut the opening etc.  It works fairly well, but does not align with the top of roof. My first attempt was with a 6" generic roof in the family editor, and when placed in my models 12" roof the dome starts at 6" below the top of roof.  There are two revolves involved, one for the cylindrical frame through the roof, and one for the dome.  I edited the cylindrical revolve and aligned and dimension locked it so that it will move correctly when I change the roof thickness.  But the dome is tougher because it includes diagonal/ curved lines (I've tried both) which I can't manage to constrain to handle the roof changes.  I align a horizontal line with the top of the cylinder revolve, but I can't get the other lines to move accordingly.  Any tips on how to do this?  For now I'll just make a flat disc of glass, but I'm hoping to have a proper dome working sooner or later.

Thanks, for any tips and here is a sketch of the simple dome shape that I've tried using (attached).  This shows the sketch for the revolve below the roof top.  I had increased the roof from 12" to 18" to test the behavior.

[barthbradley]

Constrain dome profile to frame and family should be face-based. Looks pretty doable. There are similar Velux families available through Seek. Reverse-engineer one of theirs. 

[ToanDN]

It is better to use nested families when you have to deal with constraint of complex geometry. Feel free to upload the family so that we can look at.

[chrisplyler]

Create the dome as a family by itself. A face-based family. It should have strong reference planes that cross to define it's center (revolved axis).

Then nest it into your main family (which should have matching reference planes crossing in the center (revolved axis), and place it and align/lock it to the right surface and centering reference planes.

Now it should go up and down with the top of your cylindrical frame.